Nepal disaster is a warning for Peru’s glacier defences

Benjamín Morales was seven years old when water, rocks and mud swept away his neighbours’ homes in the Peruvian Andes. He ran barefoot with hundreds of others towards higher ground as a flood killed thousands of people in Huaraz, the capital of the Ancash region: the Palcacocha glacial lake had burst. It was 13 December 1941.

“I still remember it like a film playing before my eyes,” Morales tells Dialogue Earth. The disaster would shape the course of his life.

The Peruvian geologist Benjamín Morales carrying out a topographical survey as part of his glacier monitoring work (Image supplied by Benjamín Morales)

Morales went on to become a geologist and study glaciers around the world, from his native Andes to the polar regions and the Hindu Kush Himalayas. Between the 1960s and 1990s, he led some of the most important government initiatives to reduce glacier-related risks in Peru’s Cordillera Blanca mountain range.

Morales has ultimately witnessed the three deadliest glacier-related disasters of the past 100 years, the first being the events of 1941 in Huaraz. In 1962, he saw the town of Ranrahirca destroyed after an ice block broke away from Peru’s tallest mountain, Huascarán. In 1970, Morales had just left Yungay when an earthquake triggered an avalanche on Huascarán that engulfed the town, as well as Ranrahirca, killing 25,000 people in less than 10 minutes.

Paola Moschella, who directs glacier research at Peru’s National Glaciers and Mountain Ecosystems Research Institute (Inaigem), says “studies rank the Andes as the third highest-risk region in the world” for glacial floods. The danger arises from the combination of steep tropical glaciers and densely populated communities living close to river channels.

The Himalayan glacier collapse late last month killed more than 1,300 people as it swept through the Trishuli and Bhotekoshi valleys on the Nepal-Tibet border. Thousands more were still missing as of 11 September. For Morales, the disaster has triggered deeply personal memories.

A pioneering response

Amid these glacier disasters, Peru built what became an unprecedented, state-led programme of risk prevention.

The 1941 flood prompted the first systematic efforts to monitor glacial lakes and carry out preventive works in glacier-fed basins. This led to the creation of the Comisión de Lagunas (Lakes Commission) and later the Corporación Peruana del Santa (named after Huaraz’s main river), state institutions responsible for disaster prevention works in this part of the Andes. These bodies later passed responsibility to Electroperú, the state-owned electricity generator, which carried out prevention works through to the 1990s.

Morales and his colleagues became, in effect, surgeons of the high mountains. They developed a four-step approach: lowering lake water levels in a controlled manner, building drainage tunnels, reinforcing containment dams and constructing hydraulic overflow channels. Morales says they stabilised 35 glacial lakes in the Cordillera Blanca.

“People came from all over the world to learn from what we were doing. They invited us everywhere to explain our work. We were pioneers,” Morales says.

The Peruvian glaciologist César Portocarrero has spent five decades working on glacier safety projects in the Peruvian Andes and Nepal. He recalls “the technical audacity of those years”.

Between the 1960s and 1990s, the Cordillera Blanca was the site of some of these projects. Engineers drilled through its Safuna glacier to a depth of 160 metres, carried out seismic-refraction studies and excavated a 150-metre moraine tunnel. And at lake Parón, they drilled 55 metres through solid rock using high-altitude diving and advanced technology. This work generated detailed information about the lakes, while also strengthening dams and lowering water levels to reduce the risk of catastrophic outburst floods.

The Yungay disaster also transformed Peru’s institutional response. In 1972, the government established what is now called the National Civil Defence Institute (INDECI). It was the country’s first formal institution dedicated to disaster prevention and response.

Yungay was rebuilt on safer ground, in an ambitious relocation effort. The ruins of the old city were declared a memorial site.

A system under strain

Much of that progress began to unravel around the turn of the century. Amid budget cuts in 2000, the government closed Peru’s historic Glaciology and Lake Safety Programme, which had become revered for its pioneering, standard-setting achievements.

Today, glacier management is facing a structural crisis. Alonso Brenes, a World Bank consultant and member of Unesco’s Advisory Group on Risk Management for Latin America, points to fragmented institutions and weak local governments.

Decentralisation, Brenes tells Dialogue Earth, has not been matched by the technical capacity needed to manage risk: “According to estimates, barely 35% of subnational governments in Peru have operational units capable of functioning in disaster risk management, turning prevention into little more than words on paper.”

Moschella says the limits of Inaigem’s role illustrate the problem: “We do not directly carry out preventive actions or construction works, in accordance with Peru’s legal framework. What we do is generate knowledge, assess hazards and provide technical assistance to local and regional governments, which are the legal authorities.”

Portocarrero describes a constant “passing of the buck” over the years, between the various institutions that could have been carrying out works identified as urgent by scientists.

The numbers underline the scale of the challenge. Of more than 8,000 glacial lakes assessed across Peru, Inaigem has identified 528 at risk of overflowing. Of these, 169 are in Ancash – the region where the country’s three deadliest glacier disasters of the past century have all occurred.

The infrastructure built during the 20th century is also deteriorating. The most emblematic example is Palcacocha. According to Inaigem, by 2016 the lake’s water volume had grown an estimated 34 times larger than in 1972. It also deems the dam at Palcacocha, built more than 50 years ago, to be potentially dangerous. It threatens Huaraz’s entire population of approximately 120,000, many of whom live in the same area where Morales watched his neighbours disappear.

Studies have suggested that human-caused climate change is increasing the danger the lake poses.

Brenes says economic realities leave communities with little choice but to settle in such high-risk areas: “People settle and return to high-risk areas along river channels not out of ignorance, but because of economic survival needs. They choose proximity to water for trade and agriculture, despite the latent danger.”

The confluence of two rivers in Huaraz in the Peruvian Andes, which flow down from the Cordillera Blanca mountain range (Image: Alexander Luna / Germanwatch e.V.)

The memory of past disasters has also faded. “Unlike Yungay, which was relocated, places such as Ranrahirca were rebuilt twice in the same high-risk location,” Moschella explains.

With physical mitigation infrastructure falling short, technology is being used to gain potentially lifesaving minutes. A well-operated early warning system can give communities between six and 25 minutes to evacuate before a flood, Moschella says. Inaigem has installed three real-time monitoring stations across the Andes, in Huaraz, Cusco and Huánuco, although Huaraz’s system has faced operational problems. Inaigem is also working towards implementing a warning system on the slopes of Huascarán.

The future of water for Peruvians

For policymakers, the mountains present a difficult combination of uncertainty and accelerating change. Moschella describes glacier-related disasters as “unpredictable”, adding that “calculating probabilities in the current context of climate change is extremely difficult.”

Meanwhile, Peruvian glacier retreat is accelerating. Inaigem data generated in 2023 revealed the country had lost 56% of its glacier cover during the past six decades. This is creating another, slower-moving crisis: water insecurity.

Portocarrero and Brenes estimate that 60-65% of Peru’s population depends on water regulated by river basins originating in glaciated areas. Speaking from Huaraz two years ago, the environment minister acknowledged that millions of Peruvians depend on water from mountain ecosystems. “The greatest tragedy will be running out of water,” Portocarrero adds.

Some 58% of Peruvians live in areas with water scarcity, according to the National Centre for Strategic Planning (CNPE). “Lima faces the real threat of losing, by around 2030, the reserves that supply its river basins,” Brenes says.

For Morales, Peru has already lost something that took decades to build: “Everything we achieved has been left in the past.”

His words are a warning not only for Peru but for Himalayan countries thousands of miles away. Glaciers will continue to retreat. The question is whether governments can preserve the institutional memory, technical expertise and political commitment needed to protect those living downstream – before the mountains roar again.